Ii-Placement And Installation; Iii-Charging - Lennox LGT Series Unit Information

II-PLACEMENT AND INSTALLATION

Make sure the unit is installed in accordance with the in-
stallation instructions and all applicable codes. See ac-
cessories section for conditions requiring use of the op-
tional roof mounting frame (C1CURB10).

III-CHARGING

A-Refrigerant Charge and Check
WARNING-Do not exceed nameplate charge under
any condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge, evacuate the system, and add re-
quired nameplate charge.
NOTE - System charging is not recommended below 60°F
(15°C). In temperatures below 60°F (15°C) , the charge
must be weighed into the system.
If weighing facilities are not available, or to check the
charge, use the following procedure:
IMPORTANT - Charge unit in standard cooling mode
at full load..
1 - Make sure outdoor coil is clean. Attach gauge
manifolds and operate unit at full CFM in cooling
mode with economizer disabled until system
stabilizes (approximately five minutes). Make sure
all outdoor air dampers are closed.
Mobile service app: RTU Menu>Component Test>Cool-
ing> Cooling Stage 3.
2 - Check each system separately with all stages
operating. Compare the normal operating pressures
to the pressures obtained from the gauges. Check
unit components if there are significant differences.
.
3 - Measure the outdoor ambient temperature and
the suction pressure. Refer to the charging curve to
determine a target liquid temperature
NOTE - Pressures are listed for sea level
applications.
4 - Use the same thermometer to accurately measure
the liquid temperature (in the outdoor section).
• If measured liquid temperature is higher than the
target liquid temperature, add refrigerant to the sys-
tem.
• If measured liquid temperature is lower than the
target liquid temperature, recover some refrigerant
from the system.
5 - Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added
or removed.
6 - Continue the process until measured liquid
temperature
temperature. Do not go below the target liquid
temperature when adjusting charge. .Note that
suction pressure can change as charge is adjusted.
7 - Example: At 95F outdoor ambient and a measured
suction pressure of 130psig, the target liquid
temperature is 96F. For a measured liquid
temperature of 106F, add charge in increments until
measured liquid temperature agrees with the target
liquid temperature.
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agrees with the target liquid